1. Field of the Invention
The present invention relates to a double-side and full color transfer paper for electrophotography having an improved traveling characteristic in an electrophotographic copying machine or a printer when a double-side copying operation is performed.
2. Description of the Related Art
Copying machines, printers and facsimile machines using the electrophotography are structured such that a charge pattern is formed on the surface of a photosensitive drum or a photosensitive belt containing amorphous silicon, an organic semiconductor and so forth to form a toner image by causing toner particles to adhere to the charge pattern. Then, transfer paper is brought into contact with the photosensitive surface to perform corona discharge or the like from the wire side of the paper so as to transfer the toner image to the transfer paper and fix the same with heat, pressure or the like to obtain a printed image.
Since the foregoing full color copying method uses toner in four colors, its transference mechanism is considerably different from that of the conventional white and black copying machine. It is important for the full color copying machine to accurately superimpose and transfer four color toner images. Therefore, -a transfer drum method has been employed which is arranged such that a transfer member, such as transfer paper, is supported on a transfer-member holding member, typified by a transfer drum, which is rotated in synchronization with a toner-image carrier, such as a photosensitive drum, and a toner image is transferred to the transfer paper supported around the transfer drum.
To improve productivity of the copying operation, a tandem method of forming a color image is employed by a portion of apparatuses, the method being structured such that a transference-member holding member in the form of an endless belt is employed and a plurality of image forming means corresponding to the colors are disposed along a direction in which the transference-member holding member is moved so as to sequentially transfer toner images in the respective colors on the transfer member held by the transfer-member holding member.
As described above, the transference mechanism and the like of the color copying machine are considerably different from those of the white and black copying machine. Therefore, considerably different characteristics are required for the transfer paper. Since there arise a variety of requirements in that the quality of the formed image must be improved and the state of curled paper must be stabilized, various improving means have been suggested (for example, refer to Japanese Patent Laid-Open No. 1-292354, Japanese Patent Laid-Open No. 4-268567, Japanese Patent Laid-Open No. 4-291351, Japanese Patent Laid-Open No. 4-337736, Japanese Patent Laid-Open No. 4-349468, Japanese Patent Laid-Open No. 5-341553, Japanese Patent Laid- Open No. 5-53363 and so forth).
In recent years, many color copying machines have a double-side mechanism. Thus, means for improving requirements for the double-side copy to satisfy, for example, prevention of set-off and improvement in the quality of the formed image have been suggested (refer to, for example, Japanese Patent Laid- Open No. 6-186769).
If the transfer paper suggested so as to form a color image or transfer paper which has been used in a white and black electrophotographic method is used in the double side copying operation of a copying machine using the full color electrophotographic method, a fact has been detected that a critical problem arises in the traveling characteristic, and more particularly in the traveling characteristic in a low temperature and low humidity state.